鞭毛是位于细菌表面的长螺旋形可旋转附属物,长约10 μm,主要与细菌的运动有关.鞭毛的驱动力是许多细菌病原体的重要毒力特征,并且是建立感染所必需的.感染发生后,鞭毛有利于细菌到达侵入部位.大肠杆菌(Escherichia coli,E.coli)一般周身鞭毛,具有运动性.鞭毛蛋白,又称为H抗原,是大肠杆菌分类的重要表面抗原.本文对大肠杆菌鞭毛的结构、功能和H抗原分型作一简要综述,旨在为本领域的相关研究提供一定的理论基础和依据.

To construct the deleted hcp1 and hcp2 genes of type Ⅵ secretion system (T6SS) of avian pathogenic Escherichia coli (APEC),the CE129 strain of APEC was used as the prototype strain.Then,the single gene deleted strains (CE129△hcp1 and CE129 △hcp2) and double gene deleted strain CE129 △hcp1 △hcp2 from APEC CE129 were prepared using the Red recombination system.In addition,the hcp1 and hcp2 genes were cloned into the expression vectors of pBR322 or pACYC184 to construct the complementary strains of CE129 △hcp1/phcp1,CE129 △hcp2/phcp2 and CE129 △hcp1 △hcp2/phcp1phcp2,respectively.These mutant strains and complementary strains were proved to be genetically stable confirmed by PCR and DNA sequencing.This work provided the basis to investigate the mechanism of T6SS in APEC CE129 and understand the pathogenesis of APEC.It might also help in the prevention and control of APEC-caused avian diseases.

以产肠毒素大肠埃希菌F4ac (F4ac+ ETEC)基因组DNA为模板,通过PCR扩增出Sfm菌毛操纵子顶端黏附素sfmH基因,然后将PCR产物插入原核表达载体pET-28a(+)中,构建出阳性重组质粒pET-28a(+)-sfmH,再将其导人大肠埃希菌BL21中进行诱导表达.通过对IPTG浓度、诱导温度和诱导时间进行探究,发现重组菌在0.8 mmol·L-1 IPTG、25℃诱导7h时蛋白表达量最高,且重组蛋白以包涵体形式存在,大小约为26 ku.将重组蛋白在最优诱导条件下进行大量表达并纯化,利用纯化后的重组蛋白免疫BALB/c小鼠,获得SfmH多克隆抗体(简称多抗),通过ELISA和Western blot试验对多抗效价和特异性进行鉴定.这一研究构建并获得了高纯度的融合蛋白rSfmH,将其免疫小鼠后成功获得鼠源高免血清,为进一步探究Sfm菌毛的功能奠定了研究基础.

为了分析肉鸡屠宰和鸡肉销售过程中沙门菌的污染情况,在不同季节采集江苏某地肉鸡屠宰场棉拭子样品、农贸市场和大型超市鸡肉样品进行沙门菌的分离和血清型鉴定.结果显示:492份样品中沙门菌的总检出率为16.1％,其中屠宰场样品总检出率27.1％,显著高于市场销售样品5.6％的总检出率(P＜0.001);夏季样品检出率为19.5％,高于秋季样品的13.7％,其中屠宰场样品夏季检出率46.3％,秋季则显著降至17.5％ (P＜0.001),市场销售样品夏季检出率1.7％,显著低于秋季样品的9.1％(P＜0.05);德尔卑沙门菌、肠炎沙门菌、纽波特沙门菌和印第安纳沙门菌是优势血清型.研究表明,肉鸡屠宰过程中沙门菌污染较为严重,褪毛、去内脏是交叉污染的关键环节,加强屠宰用水和环境的卫生,增加淋洗并保持冷链储运和销售等措施有助于肉鸡生产链沙门菌的有效防控.